title: First-principles study of the structural, elastic, and electronic properties of C(20), C(12)B(8), and C(12)N(8).
abstract: First-principles calculations were performed to study the structural, elastic, and electronic properties of the crystalline form of C(20), C(12)B(8), and C(12)N(8). These compounds exhibit very different elastic and electronic properties. The shear modulus of C(12)N(8) is much higher than those of C(20) and C(12)B(8). The strong covalent C-N interaction plays an important role in this high shear modulus. Compared with C(20), the relatively small Zener anisotropy of C(12)N(8) is mainly due to its large elastic constant (C(11) - C(12)). The calculated band structure shows that C(12)N(8) is an insulator with a direct band gap of 3 eV and the other two compounds (C(20) and C(12)B(8)) are metallic. Analysis of the band structure, density of states, and charge density show that the degree of filling in the non-bonding 2p(z) strongly affects the electronic properties. The full filling of the non-bonding orbital for C(12)N(8) results in its insulating behavior.
authors.affiliation: Institute for Computational Materials Science and Physics Department, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: Hong Bin
authors.initials: HB
authors.lastname: Xu
authors.forename: Yuan Xu
authors.initials: YX
authors.lastname: Wang
authors.forename: V C
authors.initials: VC
authors.lastname: Lo